US2695265A

US2695265A - Injection mixer for use in catalytic hydrocarbon conversion processes

Info

Publication number: US2695265A
Application number: US89877A
Authority: US
Inventors: William J Degnen
Original assignee: MW Kellogg Co
Current assignee: MW Kellogg Co
Priority date: 1949-04-27
Filing date: 1949-04-27
Publication date: 1954-11-23
Anticipated expiration: 1971-11-23

Description

Nov. 23, 1954 w. J. DEGNEN 2,695,265 INJECTION MIXER FOR USE IN CATALYTIC HYDROCARBON CONVERSION PROCESSES Filed April 27, 1949 FLUID FEED INVENTOR. WILLIAM J. DEGNEN ATTORNEYS INJECTION MIXER FOR USE IN CATALYTIC HYDROCARBON CONVERSION PROCESSES William J. Degnen, Wesi'field, N. J., assignor to The M. W. Kellogg Company, Jersey City, N. J., a corporation of Delaware Application April 27, 1949, Serial No. 89,877 8 Claims. (Cl. 196-52) sary to mix finely divlded ent or in polymerizing The introduction of the powdered solid into such systems has been attended by numerous difiiculties, especially in large scale operations. refining industry, where a powdered cracking catalyst heated to 1000-1159 F.

a rapidly by reason of the abrasive nature of the catalyst. This erosion not only requires the frequent replacement of expensive lines and fittings, ut also keeps exceedingly costly equipment out of -production while the new parts are being installed. By reason of their fineness and nonadhesive characteristics, such powdered catalysts may be handled similarly to fluids .in many respects and are often termed fluidized solids. In the prior art, these fluidized materials have usually been introduced into conduits from closedvessels for transportation by a high velocity stream of gases by merely flowing through the branch of a 'T the T, while at other times the materiaL-sweeps out of the vertical branch along the upper section of the transporting line. This uneven dispersal 'of the hot catalyst on first entering the carrying ternal patches. In addition severe bumping or vibration is set up when large quantities of the powdered solids are introduced into the stream in the manner described above. The present invention corrects these difiiculties to a large extent 'by injecting the finely divided catalyst into the hydrocarbon stream in such manner as to minimize erosion and bumping. It also affords -a means of measuring the quantity of catalyst added per *unit quantity of gases.

An object of the invention is to provide an improved process and apparatus for dispersing finely divided solids in gases, vapors, liquids :or mixtures thereof, such as mists or fogs, to produce chemical reactions.

A second object of the invention isfco provide a proc- For example, In the petroleum United States

Patent lines

12, 14

2,695,265 Patented Nov. 23, 1954 and means for measuring the quantities of solids in the process.

Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.

This invention is concerned with apparatus and a mac g solid into one or more flowing fluids to produce a chemical reaction rangements of parts and manner of operation, which will be exemplified in the detailed description herein, and the scope of the invention will be indicated in the claims.

The construction, operation and objects .of the present invention are best understood by reference to the accom pa-nying drawings in which:

Fig. l is a longitudinal sectional view of the injecting and mixing device;

Fig. 2 is a similar view of another modification of the invention; and

Fig. '3 is an enlarged fragmentary view of a portion of Fig. -2.

Referring to Fig. 1, a pipe line or conduit 1 through which gases, vapors or liquids are flowing at high velocity iromleft to right, contains a venturi :2. Inside the 'T' 3 a nozzle 4 in the form of a reducing L extends from the standpipe 5 supplying a finely divided catalyst '6 to the center of the conduit. The outlet orifice 7 of the L is positioned closely adjacent to, and within, the throat 8 of th of this orifice or discharge Referring to Figs. '2 and 3, vention contains a pipe 12 slidea bly mounted within a concentric pipe 13 which is integral with L 4. This construction is especially adapted for the addition through line '12 of a liquid feed which is to be vaporized by the neat of the finely divided solids 6 Where another deed streamconsisting'of gases or vapors is introduced through

pipes

14 and 15.

valve arrangements (not shown9. The modification of the invention illustrated in Fig. 2 is particularly designed for the injection of regenerated catalyst which transports it to the catalyst enters the L or nozzle 4 at an elevated temperature. Accordingly the clearance shown in -3, between pipes '12 and 13, must be adequate to allow for differences in expansion in these two lines. Although these two pipes are shown as extending to the for most purposes. that pressure taps 9, 10 and 11 be provided for this modification of the injector for the reasons set forth hereinafter.

also in vertical carrier lines with the nozzle facing either up or down depending on the direction of fluid flow. To set the device in operation a valve (not shown) is opened in the upstream side of conduit 1 to establish the flow of fluid and a second valve (not shown) in standpipe 5 is opened to the desired extent in order to admit the finelydivided solids 6 from an external source. As the stream passes through the venturi throat 8, which is the point of lowest static pressure and maximum velocity, it inducts the powder into the conduit and for a while keeps the finely divided solid material enveloped in an annular column of fluid. This fluid envelope substantially prevents the concentrated mass of powder from striking any wall'surfaces until a point downstream of the venturi outlet is reached where the stream has a lower velocity due to its greater cross-section and the finely divided solids and the fluids have become evenly dispersed in the stream. It appears that erosion in systems containing finely divided solids suspended in gases is proportional to the cube of the velocity of fiow and varies directly with the concentration of solids per unit volume. the present invention, when the powder does strike the surfaces of the conduit it is less concentrated, moving at a slower velocity than at the throat and impingement on the conduit is general rather than localized; and each of these three factors reduces erosion. Moreover, in catalyticprocesses the quicker attainment of a substantially uniform mixture of the fluid and the catalyst provides a correspondingly longer time. for reaction in the ,presencebfthe catalyst. In addition it has been observed that vibration or bumping in the conduit is far less with the-present device than where the powdered solid is allowed to drop through the branch of a T into a high velocity fluid stream. i

--In the construction of the "device herein disclosed it is preferred to have all'passages of circular cross-section, but the invention is not limited to this particular design, inasmuch as the various parts can befashioned in other shapes, as for instance a rectangular conduit, and still retain to a considerable'extent the advantages of the present invention. For maximum efficiency the wall of the inlet section of the venturi should be in the form of a truncated cone having an apex angle of approximately 25 and the wall of the outlet section should be in the form of a truncated cone having an apex angle of about 7. In other Words the walls of the converging and diverging sections of the venturi preferably slope at 12.5 and 3.5 respectively relative to the axis. ever, different angles will be observed in Figs. 1 and 2 and this is often is not feasible to build an ideal venturi because of its great length or other construction limitations. As a general rule the major be realized when theslope of the diverging section is within the range from 2 to 30, hat is, a total angle of 4 to 60 at the theoretical apex; and the slope need not be constant throughout its length The venturi segment of the conduit may example, it may consist of a metal shell of the proper configuration either replacing a section of the conduit or inserted in the conduit. Also, it may be'made by lining the pipe with re-e'nforced concrete or a castable refractory in which is embedded a metal screen, panded metal, or other suitable re-enforcement. It 1s also desirable to point out that while the throat of the venturi is shown in the accompanying illustrations as a circle, that cylindrical throats of substantial length are often used in venturis and the venturi employed here may be so fashioned. Accordingly the expressions throat and throat section are used herein to denote either type of throat.

-- -Whi1e a venturi forms a part of each of the injectors described herein the complete venturi is not an essential part'of the invention; for example, in both Figs, 1 and 2 the portion ofconduit 1 upstream of orifice 7 could have the same internal diameter as throat 8. The essential features of the present invention are a means for introducing finely divided solids at the interior of a hollow column of air followed by a passage of gradually increasing cross-section.

. The location of the orifice 7 is the full benefits of this invention, characteristics of the impingement passage. It is preferably located in the throat 8 of the venturi, for at this point the fluid is at its maximum critical in obtaining for it determines the Howthe case in large installations where it benefits of the improved injector will be constructed in various ways; for

of the powder on the .on the orifice.

-. section has been fluidized solids in that operating four months, even though a wear plate had bee 4 velocity and, therefore, exerts the greatest suction effect This minimizes the necessary build-up of standpipe pressure headto otfset the pressure drop encountered in powder circulation systems. Even more important is the fact that this location minimizes erosion as described previously. impingement of the finely divided solids on the throat must be prevented and it has been found that this can be accomplished by locating the plane of the orifice 7 not more than two-thirds of the throat diameter from the junction of the throat and the downstream diverging section of the passage. Placing the orifice a greater distance downstream results in an undesirable eddying of the fluid powder mixture. the case of a long venturi throat, locating the orifice too far upstream in the throat will result in the powder impinging on the throat. Although it is not as desirable as a location in the throat, the orifice may be positioned in the converging section slightly upstream of the throat without causing impingement on the throat provided that it is not more than from one-tenth to one-quarter of the throat diameter upstream, depending on the slope of the converging section, of the throat and not more than two-thirds of the throat diameter upstream of the diverging sec'tion.

The diameters of the orifice 7 and the throat 8 are determined by the needs of the particular installation. The fluid velocity in the throat must be substantially in excess of that required to disperse and transport the powder in order that the velocity in the larger conduit 1 will be sufficient to carry the solids in suspension. In handling cracking catalysts, it is recommended that the throat be designed to produce a static pressure drop of approximately one inch of mercury between taps 9 and 10. This will provide a fluid velocity of about to 250 feet per second at the throat in large commercial installations when the flowing medium is air at atmos pheric conditions. For'other purposes, it may be desirable to have a pressure drop ranging from as little as 0.25 up to 2001' more inches of mercury. Of course, the velocity will vary depending mainly on the density of the fluid employed. The orifice area should be adequate to introduce an excess of the catalyst inasmuch as the supply of this powder can best be adjusted by a valve in standpipe 5.

The introduction of the powdered catalyst into a vapor of a venturi l'ong gradual sloping proposed previously, but this construction cannot achieve the results of the present invention for the powder will undoubtedly produce extreme erosion at the venturi throat due to the high velocity of flow there and also concentrations of the having a rather because localized region are far above the minimum obtained upon thorough mixing of the powder and vapor.

A further advantage of the new injector is derived from the ability to measure the injection rate of the powder by means of the pressure differentials between the pressure taps 9, 10 and 11, once the device has been calibrated. To obtain this rate it is first necessary to obtain empirical data by inserting a venturi or other suitable flow meter in the upstream side of line 1 to obtain the fiow rate with air, while observing at the same time the static pressure at taps 9, 10 and 11. At various flow rates the change in the pressure differentials across taps 9, 10 and 11 are then obtained for a series of runs with varying amounts of finely divided solids introduced into the system. Alternatively, a calibration can also be made of a small model of the-injector and the resulting data applied to a large scale installation of similar aerodynamic an geometric characteristics where direct calibration of the large unit is not feasible.

The mixer herein described has proven greatly superior in commercial regeneration of a cracking catalyst over cracking unit the carrier installed to re-enforce the pipe at this point. T was replaced with the device shown in Fig. l equippe with a venturi of refractory material; erosion from the highly heated catalyst as indicated b local hot spots could be detected by careful measureme of the temperatures at numerous points on the exteri of the supply line at frequent intervals during more th W stresses ten months or eon'tinuo'us operation. It was also obtei'ior efen" annular portion at thefiuid stream inside the served that faf less bumping occurred in this line even venturi threat, thereafter gradually expandin the crossthough the system due to other conditions was being seeno ais rea of the mixed stream to reduce its excess lthough th1s invention has been described prmcimg t e ow rates of the fluid and the solid material to pally in connection with the refinm of petroleum and is provide predetermined static pressure dlfierentials between partlcularly adaptable to apparatus for cracking, reformthe inlet and throat and between the throat and outlet ing, hydrogenating and polymerizing hydrocarbon gases of the venturi, the solid material being introduced at a or vapors; it nevertheless is useful for many other pup point within two-thirds of the venturi throat diameter poses, as for example, mixingfinely divided aluminum from the junction of the throat and the downstream di into a stream of chlorine to form aluminum chloride. vergin section of the venturi.

In general, any powdered catalyst or reactant may be in 5. A process for intimately and uniformly mixing a troduced and mixed into any suitable fluid to produce a h finely divided solid material into fluids to produce a chemical reaction by means of the device described chemical reaction which comprises passing a fluid along herein. a passage having a throat section of minimum cross Since the changes have been made in the above consection at a velocity substantially in excess of that restruction which embodies the invention, without departquired to disperse and transport the solid material contained in the above detailed description or shown at substantially the center of the stream of said fluid illustrative and not in a irniting sense. thereafter gradually expanding the cross-sectional area of It is also to be understood that the following alarms t e mixed stream to reduce its excess velocity while are intended to cover all the generic and spec1fic features transporting and mamtammg the SOlld material in subof the invention herein described, and all statements of stantially uniform dispersion, the solid material being the scope of the invention, which as a matter of language introduced at a point within two thirds of the minimum might be said to fall therebetween. dimension across the throat section from the beginning Having described my invention, What I claim as new of the zone of expansion of cross-sectional area and not and desire to secure by Letters Patent, is: more than one-quarter of said minimum dimension up- 1. A process for intimately and uniformly mixing a Stre m f the throat Section. finely divided solid material into a fluid to produce a 6. A process for intimately and uniformly mixing chemical reaction which comprises passing the fluid along a finely divided solid material into fluids to produce a a passage having a throat section of minimum cross-seer; c emical reaction WhlCh comprises passing a fluid tron at a velocity substantially in excess of that required rough a throat section of minimum internal diamto disperse and transport the SOlld material in the fluid, eter in a passage of substantially circular cross-section introducing the solid material at substantially the center at a velocity substantially in excess of that required SOlld material being introduced at a point within twomaterial whereby said l1qu1d 1s vaporized, and theret irds of the minimum dimension across the throat secafter gradually expanding the cross-sectional area of tron from the beginning of the zone of expansion of the mixed stream to reduce its excess velocity While transcross-sectional area and not more than one-quarter of porting and maintaining the solid-material in substan said minimum dimension upstream of the throat section. tially uniform dispersion, the solid material being in- A process for intimately and uniformly mixing a troduced at a point within a distance equal to two-thirds finely dlvlded solid material into a fluid to produce a of the throat dlameter from the begmnmg of the zone chemical reaction which comprises passing the fluid of expansion of cross-sectional area and not more than through a throat section of minimum internal diameter one-quarter of the throat diameter upstream of the in a passage of substantially circular cross-section at a hr at Section. velocity substantially in excess of that required to dis- 7. A hydrocarbon conversion process wherein a hyperse and transport the solid material in the fluid introdrocarbon reactant is contacted with a fluid mass of duclng the solid material at the interlor of an annular finely dlvlded eatalyhc Pafheles III a a l n Z n hus portion of the fluid stream, and thereafter gradually exproducing converted hydrocarbon products and conpanding the cross-sectional area of the mixed stream to taminating said catalyst with a carbonaceous deposit, reduce its excess velocity while transporting and mainand wherein at least a Portion of the Catalyst in the taining the solid material in substantially uniform disaction zone is withdrawn for regeneration by treatment persion, the solid material being introduced at a point Wlt all oxygeh'cohtalnlhg gas 111 a regeneration Z0116; within two-thirds of the throat diameter from the be- 6 Improvement Whwh comprlses passlng a fi rginning of the zone of expansion of cross-sectional area thl'ollgh a Zone havlllg a throat ion Of and not more than one-quarter of the diameter of the minimum cross-sectional area at a VClOCltY In excess Of throat section upstream of the throat section. h leqhlred t0 dlsperse and transport the finely process for i t l d umformly mlxmg a vided catalyst introducing catalyst from one of the chemical reaction which comprises passing the fluid earfl'el Stream, P the mixture of Catalyst an of an annular portion of the fluid stream, and thereafter t rough e diVelgihg Z0he for Passage t0 the other of gradually expanding the cross-sectional area of the mixed the afofesald Processing Zones, the catalyst being stream to reduce its excess velocity while transporting troduced through an injection Z9116 facing downstream and maintaining the solid material in substantially unithe discharge thereof 18 oca ed Within twoform dispersion, the solid material being introduced thirds of the throat diameter from the juncture of the through a substantially circular orifice facing downstream throat Section and the downstream diverging Zone and and located within two-thirds of the venturi throat dinot more than one-quarter of the throat diameter P- ameter from the junction of the throat and the downstream of the throat SeetlOIltream diverging section of the venturi and not more A hydrocarbon Conversion Process wherein a yan one-quarter of the throat diameter upstream of the drocarbon reactant is contacted With a fluid mass Of enturi throat. finely divided catalytic particles thus producing a con- 4 A process for i i l d u if l mixing a verted hydrocarbon product and contaminating the catnely divided solid material into a fluid to produce a alyst' Wllh a carbonaceous deposit wherein at least. a emical reaction which comprises passing the fluid portlon of the catalyst in the reaction zone 1s withrough a venturi at a velocity substantially in excess of drawn for l'egenel'atloll by treatment Wlth an y at requlred to disperse and transport the solid material contarnmg gas in a regeneratlon zone the improvement a 2056 having a threat sectjion ogummim' um crosfs-tsgc- Y References Cited in the file of this patent tion area at a we ocity su stanti y in excess 0 at p a required to disperse and transport the catalyst, intro- UNITED STATES PATENTS ducing the catalyst from one of the aforesaid process- Number Name Date ing zones into the interior of the fluid carrier stream, 5 1,475,502 Manning Nov. 27, 1923 passing the mixture of catalyst and fluid carrier stream 2,054,441 Peebles Sept. 15, 1936 through a diverging zone of gradually expanding cross- 2,231,424 Huppke Feb. 11, 1941 sectional area to reduce the velocity and substantially 2,326,438 Clarke Aug. 10, 1943 avoid eddying of said mixture while flowing through the 2,486,228 Udale Oct. 25, 1949 diverging zone for passage to the other of the aforesaid 10 2,541,662 Palmer Feb. 13, 1951 processing zones, the catalyst being introduced through a substantially circular injection zone facing down stream and having the discharge end situated within Number Country Date the aforesaid throat section of minimum cross-sectional 320,391 Grfla Britain 1929 area of the throat section and a section upstream thereof 15 for the velocity of fluid carrier stream is suflicient to eifect a static pressure drop of about one inch of mercury.

FOREIGN PATENTS

Claims

7. A HYDROCARBON CONVERSION PROCESS WHEREIN A HYDROCARBON REACTANT IS CONTACTED WITH A FLUID MASS OF FINELY DIVIDED CATALYTIC PARTICLES IN A REACTION ZONE THUS PRODUCING CONVERTED HYDOCARBON PRODUCTS AND CONTAMINATING SAID CATALYST WITH A CARBONACEOUS DEPOSIT, AND WHEREIN AT LEAST A PORTION OF THE CATALYST IN THE REACTION ZONE IS WITHDRAWN FOR REGENERATION BY TREATMENT WITH AN OXYGEN-CONTAINING GAS IN A REGENERATION ZONE; THE IMPROVEMENT WHICH COMPRISES PASSING A FLUID CARRIER STREAM THROUGH A ZONE HAVING A THROAT SECTION OF MINIMUM CROSS-SECTIONAL AREA AT A VELOCITY IN EXCESS OF THAT REQUIRED TO DISPERSE AND TRANSPORT THE FINELY DIVIDED CATALYST, INTRODUCING CATALYST FROM ONE OF THE AFORESAID PROCESSING ZONES INTO THE INTERIOR OF THE FLUID CARRIER STREAM, AND PASSING THE MIXTURE OF CATALYST AND FLUID THROUGH A DIVERGING ZONE OF GRADUALLY EXPANDING CROSS-SECTIONAL AREA TO REDUCE THE VELOCITY AND SUBSTANTIALLY AVOID EDDYING OF THE SAID MIXTURE WHILE FLOWING THROUGH THE DIVERGING ZONE FOR PASSAGE TO THE OTHER OF THE AFORESAID PROCESSING ZONES, THE CATALYST BEING INTRODUCED THROUGH AN INJECTION ZONE FACING DOWNSTREAM AND THE DISCHARGE END THEREOF IS LOCATED WITHIN TWOTHIRDS OF THE THROAT DIAMETER FROM THE JUNCTURE OF THE THROAT SECTION AND THE DOWNSTREAM DIVERGING ZONE AND NOT MORE THAN ONE-QUARTER OF THE THROAT DIAMETER UPSTREAM OF THE THROAT SECTION.